This is
a close up of Perna viridis growing on the "high" profile concrete
rubble (north of the1000 ft. pier at Ft. Desoto, St. Petersburg, July 29,
2000) in the upper intertidal area growing among oysters, barnacles and
algae.This is an area of high wave
energy, "long" periods of exposure to air, and constant
sandblasting.